The EPA's Pacific Southwest region directed its enforcement actions to the nine sewage collection systems in the Sausalito and Mill Valley areas.
Deteriorated conditions of the sewer systems became evident when heavy rains overwhelmed the systems causing more than 5 million gallons to flow into Richardson and San Francisco bays earlier this year, the EPA said.
"These small, under-funded and under-managed systems will continue to pose threats to San Francisco Bay if communities fail to upgrade and maintain their systems sustainably," said Alexis Strauss, the EPA's Water Division director for the Pacific Southwest region.
"We urge the systems to begin to work together and invest in long-overdue assessment, repair and replacement of their wastewater infrastructure," Strauss said.
The EPA's orders require the sewage collection systems to employ strategies to reduce spills and in the short term, start aggressive sewer cleaning programs on the most problematic pipes. The EPA also called for inspection of the sewer pipes and to measure wet weather flows that are passed on to the sewerage treatment plants.
The EPA also called on the sewage collection systems in southern Marin County to develop plans to manage excess water flows and start long-term programs to repair and replace deteriorated sewer pipes and to work together to finance, operate and renew their wastewater infrastructure.
Stephen Danehy, manager of the Sewage Agency of Southern Marin's treatment plant, said he had not yet seen the EPA's report and recommendations, but that they sounded like a reinforcement of sewer system management plans each agency should already have in place.
"A coordinated approach would benefit us all in the long run," Danehy said this afternoon. "There would be far less expense doing it together," he said.
The 5 million gallons that spilled into Richardson Bay happened at the Sewage Agency of Southern Marin's treatment plant on Jan. 25 and 31. The EPA found that deteriorating pipes combined with extreme peak flows from rainwater overwhelmed the plant causing storm water and partially treated sewage to exceed the capacity of holding basins on Jan. 25.
The EPA said the Jan. 21 spill was caused when the plant failed to operate all its discharge pumps to achieve higher levels of treatment offsite.
Danehy said the Sewage Agency of Southern Marin is still working on correcting immediate deficiencies. A contractor next week will begin replacing 25-year-old effluent pumps that remove water from the plant, he said.